Vector-matrix multiply operations are highly computationally intensive and are needed for such applications as eigenmode calculations and decoding algorithms. The ability to perform vector-matrix multiplication at a high rate of speed is also needed for many computationally intensive applications including synthetic aperture radar and image processing (both 2D and 3D). Traditional digital computers and even vectorizing machines are limited in their ability to perform such computations at high rates of speed. Current state-of-the-art digital computers can achieve about ten billion (1010) floating point operations per second. Despite this seemingly high rate of computation, codes for electromagnetic and quantum systems, for example, often require highly parallel digital computers, which are quite large and power intensive, to run for days at a time to achieve a result. This is insufficient for many applications which require real time data processing.
Over the past few decades, different types of optical vector-matrix multipliers have been proposed as a way of speeding up vector-matrix multiplication (see e.g. U.S. Pat. Nos. 3,944,820; 4,633,428; 4,937,776; 5,448,749; 6,894,827; and U.S. Patent Application Publication No. 2004/0243657). Most of these prior art approaches to vector-matrix multiplication are based on free-space optical signal processing approaches which suffer from a number of difficulties: (1) the resulting processors are cumbersome, (2) the manufacturing process is difficult to control, (3) exotic electro-optical materials are required to implement spatial light modulators (SLMs) required to encode matrix information, with the SLMs being relatively expensive and having a poor light transmission quality, (4) there is significant cross-talk and a poor signal quality, (5) it is difficult to uniformly illuminate the SLMs, and (6) there is generally an inefficient use of the available optical bandwidth. In the end, these prior art vector-matrix multipliers are large; they tend to have poor bit-error-rates; and they exhibit much lower performance than should be possible given the vast optical bandwidth that they utilize.
The present invention provides an integrated optic vector-matrix multiplier which utilizes wavelength-division-multiplexing (WDM) technology and semiconductor microfabrication to provide a compact device which can carefully allocate an available optical bandwidth while minimizing cross-talk.
The integrated optical vector-matrix multiplier of the present invention can also provide a precise representation of the vector and matrix elements, and can operate with electrical and optical inputs and outputs.
These and other advantages of the present invention will become evident to those skilled in the art.